Substituted pyridine herbicidal agents

ABSTRACT

There are provided substituted pyridine compounds having the structural formula I ##STR1## Further provided are compositions and methods comprising those compounds for the control of undesirable plant species.

This application claims priority from the co-pending provisionalapplication 60/012,055 filed Feb. 22, 1996.

BACKGROUND OF THE INVENTION

Weeds cause tremendous global economic losses by reducing crop yieldsand lowering crop quality. In the United States alone, agronomic cropsmust compete with hundreds of weed species.

In spite of the commercial herbicides available today, damage to cropscaused by weeds still occurs. Accordingly, there is ongoing research tocreate new and more effective herbicides.

Certain pyridine derivatives are known to have herbicidal activity (U.S.Pat. No. 3,535,328; EP-A2-447004; EP-A1-488474; EP-A1-537816; andEP-A1-572093). However, none of those publications describe theherbicidal agents of the present invention.

It is therefore an object of the present invention to provide compoundswhich are effective for controlling undesirable plant species.

It is also an object of the present invention to provide methods forcontrolling undesirable plant species.

Those and other objects of the present invention will become moreapparent from the detailed description thereof set forth below.

SUMMARY OF THE INVENTION

The present invention describes substituted pyridine compounds which areuseful as herbicidal agents.

The substituted pyridine compounds of the present invention have thestructural formula I ##STR2## wherein A and B are each independently

phenyl optionally substituted with one or more halogen atoms, nitrogroups, cyano groups, amino groups, hydroxyl groups, C₁ -C₄ alkylgroups, C₁ -C₄ haloalkyl groups, C₁ -C₄ alkoxy groups, C₁ -C₄ haloalkoxygroups or C₁ -C₄ haloalkylsulfonyl groups,

1- or 2-naphthyl optionally substituted with one or more halogen atoms,nitro groups, cyano groups, amino groups, hydroxyl groups, C₁ -C₄ alkylgroups, C₁ -C₄ haloalkyl groups, C₁ -C₄ alkoxy groups, C₁ -C₄ haloalkoxygroups or C₁ -C₄ haloalkylsulfonyl groups, or

a 5- or 6-membered nitrogen-containing heteroaromatic ring optionallysubstituted with one or more halogen atoms, nitro groups, cyano groups,amino groups, hydroxyl groups, C₁ -C₄ alkyl groups, C₁ -C₄ haloalkylgroups, C₁ -C₄ alkoxy groups, C₁ -C₄ haloalkoxy groups or C₁ -C₄haloalkylsulfonyl groups;

X and Y are each independently O or S;

R is C₁ -C₆ alkyl, C₁ -C₆ haloalkyl, C₁ -C₆ alkoxy, C₁ -C₆ haloalkoxy,C₁ -C₆ alkylthio or di(C₁ -C₆ alkyl)amino;

m is an integer of 0, 1 or 2; and

n is an integer of 0 or 1.

This invention also relates to compositions containing those compoundsand methods for using those compounds and compositions. Advantageously,it has been found that the compounds of the present invention, andcompositions containing them, are useful for the control of undesirableplant species.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a method for controlling undesirableplant species which comprises applying to the foliage of said plants orto the soil or water containing seeds or other propagating organsthereof, a herbicidally effective amount of a formula I, substitutedpyridine compound.

The substituted pyridine compounds of the present invention have thestructural formula I ##STR3## wherein A and B are each independently

phenyl optionally substituted with one or more halogen atoms, nitrogroups, cyano groups, amino groups, hydroxyl groups, C₁ -C₄ alkylgroups, C₁ -C₄ haloalkyl groups, C₁ -C₄ alkoxy groups, C₁ -C₄ haloalkoxygroups or C₁ -C₄ haloalkylsulfonyl groups,

1- or 2-naphthyl optionally substituted with one or more halogen atoms,nitro groups, cyano groups, amino groups, hydroxyl groups, C₁ -C₄ alkylgroups, C₁ -C₄ haloalkyl groups, C₁ -C₄ alkoxy groups, C₁ -C₄ haloalkoxygroups or C₁ -C₄ haloalkylsulfonyl groups, or

a 5- or 6-membered nitrogen-containing heteroaromatic ring optionallysubstituted with one or more halogen atoms, nitro groups, cyano groups,amino groups, hydroxyl groups, C₁ -C₄ alkyl groups, C₁ -C₄ haloalkylgroups, C₁ -C₄ alkoxy groups, C₁ -C₄ haloalkoxy groups or C₁ -C₄haloalkylsulfonyl groups;

X and Y are each independently O or S;

R is C₁ -C₆ alkyl, C₁ -C₆ haloalkyl, C₁ -C₆ alkoxy, C₁ -C₆ haloalkoxy,C₁ -C₆ alkylthio or di(C₁ -C₆ alkyl)amino;

m is an integer of 0, 1 or 2; and

n is an integer of 0 or 1.

Preferred formula I substituted pyridine compounds of this invention arethose wherein

A and B are each independently

phenyl optionally substituted with one or more halogen atoms, C₁ -C₄alkyl groups, C₁ -C₄ haloalkyl groups, C₁ -C₄ alkoxy groups, C₁ -C₄haloalkoxy groups or C₁ -C₄ haloalkylsulfonyl groups, or a pyridyl,pyrazolyl, imidazolyl, triazolyl, isoxazolyl, tetrazolyl, pyrazinyl,pyridazinyl or triazinyl group each optionally substituted with one ormore halogen atoms, C₁ -C₄ alkyl groups, C₁ -C₄ haloalkyl groups, C₁ -C₄alkoxy groups, C₁ -C₄ haloalkoxy groups or C₁ -C₄ haloalkylsulfonylgroups;

X and Y are each independently O or S;

R is C₁ -C₄ alkyl, C₁ -C₄ haloalkyl, C₁ -C₄ alkoxy, C₁ -C₄ haloalkoxy,C₁ -C₄ alkylthio or di(C₁ -C₄ alkyl)amino; and

m and n are each independently an integer of 0 or 1.

More preferred formula I herbicidal agents of the present invention arethose wherein

A and B are each independently

phenyl optionally substituted with one to three halogen atoms, C₁ -C₄alkyl groups or C₁ -C₄ haloalkyl groups, or

a pyridyl or pyrazolyl group each optionally substituted with one tothree halogen atoms, C₁ -C₄ alkyl groups or C₁ -C₄ haloalkyl groups;

X and Y are O;

R is C₁ -C₄ alkyl, C₁ -C₄ haloalkyl, C₁ -C₄ alkoxy or C₁ -C₄ haloalkoxy;and

m and n are each independently an integer of 0 or 1.

Most preferred formula I herbicidal agents of the present invention arethose wherein

A is phenyl optionally substituted with one chlorine atom ortrifluoromethyl group,

4-pyridyl optionally substituted with one chlorine atom ortrifluoromethyl group, or

5-pyrazolyl optionally substituted with one or two methyl groups ortrifluoromethyl groups;

B is phenyl optionally substituted with one or two fluorine atoms,chlorine atoms, methyl groups or trifluoromethyl groups,

2- or 4-pyridyl optionally substituted with one or two fluorine atoms,chlorine atoms, methyl groups or trifluoromethyl groups, or

5-pyrazolyl optionally substituted with one or two methyl groups ortrifluoromethyl groups;

X and Y are O; and

m and n are 0.

Substituted pyridine compounds of the present invention which areparticularly effective herbicidal agents include

2- (2-chloro-4-pyridyl)oxy!-6-{(2-chloro-4-pyridyl)oxy!-methyl}pyridine;

2- (2-chloro-4-pyridyl)oxy!-6-{(α,α,α-trifluoro-m-tolyl)oxy!methyl}pyridine;

2- (α,α,α,-trifluoro-m-tolyl)oxy!-6-{(α,α,.alpha.-trifluoro-m-tolyl)oxy!methyl}pyridine;

2-{ (2-chloro-4-pyridyl)oxy!methyl}-6-(α,α,α-trifluoro-m-tolyl)oxy!pyridine;

2-{ (6-chloro-2-pyridyl)oxy!methyl}-6-(α,α,α-trifluoro-m-tolyl)oxy!pyridine;

2- (m-fluorophenoxy)methyl!-6- (α,α,α-trifluoro-m-tolyl)oxy!pyridine;

2- (m-fluorophenoxy)methyl!-6-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}pyridine;

2- (p-fluorophenoxy)methyl!-6-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}pyridine;

2-{ 1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-6-(o-tolyloxy)methyl!pyridine;

2-{ 1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-6-(m-tolyloxy)methyl!pyridine;

2-{ 1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-6-(p-tolyloxy)methyl!pyridine;

2- (3,5-difluorophenoxy)methyl!-6-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}pyridine;

2-{ 1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-6-(α,α,.alpha.-trifluoro-m-tolyloxy) methyl!pyridine;

2-{ (2-chloro-4-pyridyl)oxy!methyl}-6-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}pyridine; and

2-{ 1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-6-{{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}methyl}-pyridine, amongothers.

Exemplary of halogen hereinabove are fluorine, chlorine, bromine andiodine. The terms "C₁ -C₆ haloalkyl", "C₁ -C₄ haloalkyl", "C₁ -C₆haloalkoxy", "C₁ -C₄ haloalkoxy" and "C₁ -C₄ haloalkylsulfonyl" aredefined as a C₁ -C₆ alkyl group, a C₁ -C₄ alkyl group, a C₁ -C₆ alkoxygroup, a C₁ -C₄ alkoxy group and a C₁ -C₄ alkylsulfonyl groupsubstituted with one or more halogen atoms, respectively.

The substituted pyridine compounds of the present invention may beprepared by

a) reacting a 2-cyano-6-halopyridine of formula II with an alcohol orthiol of formula III and a base such as a metal carbonate or metalhydride in the presence of an inert solvent such asN,N-dimethylformamide, dimethyl sulfoxide, sulfolane, tetrahydrofuran ordioxane, preferably at an elevated temperature, to form a substitutedpicolinonitrile of formula IV,

b) hydrolyzing the substituted picolinonitrile with an acid or base inthe presence of water, preferably at an elevated temperature, to form asubstituted picolinic acid of formula V,

c) reacting the substituted picolinic acid with a phosphorus oxyhalideor thionyl halide at an elevated temperature to form a substitutedpicolinic acid halide of formula VI,

d) reacting the substituted picolinic acid halide with a C₁ -C₄ alcoholand a base such as pyridine or triethylamine in the presence of an inertsolvent such as diethyl ether or ethyl acetate to form a substitutedpicolinate of formula VII,

e) reducing the substituted picolinate with a reducing agent such asdiisobutyl aluminum hydride or aluminum hydride in the presence of aninert solvent such as diethyl ether and tetrahydrofuran at a temperaturerange of about -78° C. to 0° C. to form a substituted 2-pyridinemethanolof formula VIII,

f) reacting the substituted 2-pyridinemethanol with a phosphorusoxyhalide or thionyl halide to form a substituted 2-halomethylpyridineof formula IX, and

g) reacting the substituted 2-halomethylpyridine with an alcohol orthiol of formula X and a base such as a metal carbonate or metal hydridein the presence of an inert solvent such as N,N-dimethylformamide,dimethyl sulfoxide, sulfolane, tetrahydrofuran or dioxane, preferably atan elevated temperature, to form the desired formula I substitutedpyridine. The reaction scheme is shown in Flow Diagram I. ##STR4##

The substituted pyridine compounds of the present invention areeffective herbicidal agents useful for the control of a wide variety ofundesirable plant species. Those compounds are effective for controllingweeds native to both dry land and wet land areas when applied to thefoliage thereof or to soil or water containing seeds or otherpropagating organs thereof such as stolons, tubers or rhizomes, at ratesof from about 0.016 to 4.0 kg/ha and preferably from about 0.1 to 2.0kg/ha.

While the substituted pyridine compounds of this invention are effectivefor controlling undesirable plant species when employed alone, they mayalso be used in combination with other biological chemicals, includingother herbicides.

The formula I compounds of this invention may be applied to crops in theform of a solid or liquid herbicidal composition, comprising aherbicidally effective amount of the formula I compound dispersed ordissolved in an agronomically acceptable, inert solid or liquid carrier.The compositions may be applied as preemergence or postemergencetreatments.

The formula I compounds may be formulated as emulsifiable concentrates,wettable powders, granular formulations, flowable concentrates and thelike.

In order to facilitate a further understanding of the invention, thefollowing examples are presented primarily for the purpose ofillustrating more specific details thereof. The invention should not bedeemed limited by the examples as the full scope of the invention isdefined in the claims.

EXAMPLE 1 Preparation of 6- (2-Chloro-4-pyridyl)oxy!picolino-nitrile##STR5##

A mixture of 2-chloro-4-hydroxypyridine (38.9 g, 0.3 mol),2-chloro-6-cyanopyridine (45.7 g, 0.3 mol), and potassium carbonate(45.6 g, 0.3 mol) in N,N-dimethylformamide is refluxed for three hours,cooled and diluted with water and ethyl acetate. The resultant mixtureis filtered through a layer of silica gel using ethyl acetate as eluent.The phases are separated and the aqueous phase is extracted with ethylacetate. The organic extract is combined with the organic phase and theresultant solution is washed with brine, dried over anhydrous magnesiumsulfate, and concentrated in vacuo to obtain a residue. Flash columnchromatography of the residue using silica gel and a 7:3 hexane/ethylacetate solution gives the title product as light brown crystals (56.5g, 81.3%, mp 114° C.).

Using essentially the same procedure, the following compounds areobtained:

    ______________________________________                                         ##STR6##                                                                     A                 mp °C.                                               ______________________________________                                         ##STR7##         oil                                                          ##STR8##         92                                                          ______________________________________                                    

EXAMPLE 2 Preparation of 6- (2-Chloro-4-pyridyl)oxy!picolinic acid##STR9##

A mixture of 6- (2-chloro-4-pyridyl)oxy!picolino-nitrile (56.2 g, 0.24mol) in concentrated hydrochloric acid (60 mL) is refluxed for threehours, cooled and basified to a pH value greater than 10 with 50% sodiumhydroxide solution. The resultant solution is washed three times withdiethyl ether and acidified with concentrated hydrochloric acid to forma precipitate. The precipitate is collected, washed with water andrecrystallized from isopropanol to give the title product as colorlesscrystals (28 g, 46.6%, mp 183° C.).

Using essentially the same procedure, the following compounds areobtained:

    ______________________________________                                         ##STR10##                                                                    A                 mp °C.                                               ______________________________________                                         ##STR11##         95                                                          ##STR12##        191                                                         ______________________________________                                    

EXAMPLE 3 Preparation of Methyl 6- (2-chloro-4-pyridyl)oxy!-picolinate##STR13##

A mixture of 6- (2-chloro-4-pyridyl)oxy!picolinic acid (28 g, 0.11 mol)and thionyl chloride (50 mL) is refluxed for two hours and concentratedin vacuo to remove residual thionyl chloride. A solution of theresultant acid chloride in ethyl acetate is cooled, treated withtriethylamine (55 mL, 0.4 mol) and anhydrous methanol (5.4 mL, 0.13mol), stirred at room temperature for three hours, and diluted withwater. The organic layer is separated, dried over anhydrous magnesiumsulfate, and concentrated in vacuo to obtain a residue. Flash columnchromatography of the residue using silica gel and a 1:1 hexane/ethylacetate solution gives the title product as light green crystals (18.1g, 62.3%, mp 89° C.).

Using essentially the same procedure, the following compounds areobtained:

    ______________________________________                                         ##STR14##                                                                    A                 mp °C.                                               ______________________________________                                         ##STR15##        oil                                                          ##STR16##        108                                                         ______________________________________                                    

EXAMPLE 4 Preparation of 6- (2-Chloro-4-pyridyl)oxy!-2-pyridinemethanol##STR17##

A one molar solution of diisobutylaluminum hydride in tetrahydrofuran(200 mL, 0.2 mol) is added over 45 minutes to a solution of methyl 6-(2-chloro-4-pyridyl)-oxy!picolinate (18.15 g, 0.069 mol) in diethylether (300 mL) at -50° C. Under a nitrogen atmosphere. The reactionmixture is stirred at -50° C. for two hours, allowed to warm to 0° C.,and acidified with dilute hydrochloric acid. The phases are separatedand the aqueous phase is extracted with diethyl ether. The organicextracts are combined with the organic phase and the resultant solutionis washed with saturated sodium hydrogen carbonate solution, dried overanhydrous magnesium sulfate, and concentrated in vacuo to obtain an oil.Flash column chromatography of the oil using silica gel and a 7:3hexane/ethyl acetate solution gives the title product as a colorless oil(10.2 g, 62.5%).

Using essentially the same procedure, the following compounds areobtained:

    ______________________________________                                         ##STR18##                                                                    A                 mp °C.                                               ______________________________________                                         ##STR19##        oil                                                          ##STR20##        oil                                                         ______________________________________                                    

EXAMPLE 5 Preparation of 2-(Chloromethyl)-6-(2-chloro-4-pyridyl)oxy!pyridine ##STR21##

A mixture of 6- (2-chloro-4-pyridyl)oxy!-2-pyridine-methanol (10.2 g,0.043 mol) and thionyl chloride (10 mL) is stirred at room temperaturefor 90 minutes. Excess thionyl chloride is hydrolyzed by adding water tothe reaction mixture until no further reaction is observed. The reactionmixture is then neutralized with saturated sodium hydrogen carbonatesolution and extracted with dichloromethane. The organic extracts arecombined, dried over anhydrous magnesium sulfate, and concentrated invacuo to obtain the title product (10.6 g, 97%).

Using essentially the same procedure, the following compounds areobtained:

    ______________________________________                                         ##STR22##                                                                    A                 mp °C.                                               ______________________________________                                         ##STR23##        oil                                                          ##STR24##        51                                                          ______________________________________                                    

EXAMPLE 6 Preparation of 2- (2-Chloro-4-pyridyl)oxy!-6-(p-fluorophenoxy)methyl!pyridine ##STR25##

A mixture of 2-(chloromethyl)-6- (2-chloro-4-pyridyl)oxy!pyridine (1.66g, 6.5 mmol), 4-fluorophenol (0.89 g, 8 mmol), and potassium carbonate(1.1 g, 8 mmol) in N,N-dimethylformamide (5 mL) is refluxed for 90minutes, cooled, and diluted with a 1:1 hexane/ethyl acetate solution(100 mL). The organic mixture is then filtered through a layer of silicagel using a 1:1 hexane/ethyl acetate solution as eluent. The resultantsolution is concentrated in vacuo to obtain an oil. Flash columnchromatography of the oil using silica gel and a 8:2 hexane/ethylacetate solution gives the title product as colorless crystals (1.5 g,70%, mp 103° C.).

Using essentially the same procedure, the following compounds areobtained:

    ______________________________________                                         ##STR26##                                                                    A            B              n       mp °C.                             ______________________________________                                         ##STR27##                                                                                  ##STR28##     0       87                                         ##STR29##                                                                                  ##STR30##     0       oil                                        ##STR31##                                                                                  ##STR32##     0       111                                        ##STR33##                                                                                  ##STR34##     0       81                                         ##STR35##                                                                                  ##STR36##     0       oil                                        ##STR37##                                                                                  ##STR38##     0       oil                                        ##STR39##                                                                                  ##STR40##     0       oil                                        ##STR41##                                                                                  ##STR42##     0       87                                         ##STR43##                                                                                  ##STR44##     0       oil                                        ##STR45##                                                                                  ##STR46##     0       oil                                        ##STR47##                                                                                  ##STR48##     0       oil                                        ##STR49##                                                                                  ##STR50##     0       58                                         ##STR51##                                                                                  ##STR52##     0       oil                                        ##STR53##                                                                                  ##STR54##     0       oil                                        ##STR55##                                                                                  ##STR56##     0       oil                                        ##STR57##                                                                                  ##STR58##     0       oil                                        ##STR59##                                                                                  ##STR60##     0       oil                                        ##STR61##                                                                                  ##STR62##     0       oil                                        ##STR63##                                                                                  ##STR64##     0       oil                                        ##STR65##                                                                                  ##STR66##     0       oil                                        ##STR67##                                                                                  ##STR68##     0       oil                                        ##STR69##                                                                                  ##STR70##     0       oil                                        ##STR71##                                                                                  ##STR72##     0       oil                                        ##STR73##                                                                                  ##STR74##     0       45                                         ##STR75##                                                                                  ##STR76##     0       76                                         ##STR77##                                                                                  ##STR78##     0       oil                                        ##STR79##                                                                                  ##STR80##     0       oil                                        ##STR81##                                                                                  ##STR82##     0       93                                         ##STR83##                                                                                  ##STR84##     0       oil                                        ##STR85##                                                                                  ##STR86##     0       58                                         ##STR87##                                                                                  ##STR88##     0       oil                                        ##STR89##                                                                                  ##STR90##     0       oil                                        ##STR91##                                                                                  ##STR92##     1       oil                                       ______________________________________                                    

EXAMPLE 7 Postemergence herbicidal evaluation of test compounds

The postemergence herbicidal activity of the compounds of the presentinvention is demonstrated by the following tests, wherein a variety ofdicotyledonous and monocotyledonous seedling plants are sprayed withformulations containing test compounds. The test compounds are dispersedin an acetone solution containing 0.4% by weight of TRITON®X-155, analkylphenyl ethylene oxide condensate available from Union CarbideCorporation, Danbury, Conn. The acetone mixtures are then diluted withwater to provide the equivalent of about 0.48, 0.30 or 0.24 kg perhectare of test compound in a volume equivalent to 400 liters perhectare, and sprayed onto the seedling plants. After spraying, theplants are placed on greenhouse benches and are cared for in the usualmanner, commensurate with conventional greenhouse practices. Twenty daysafter treatment, the seedling plants are examined and rated on a 0-9scale.

The scale is based upon a visual observation of plant stand, vigor,malformation, size, chlorosis and overall plant appearances as comparedwith a control. A rating of 0 indicates no herbicidal effect and arating of 9 indicates complete kill.

Data obtained are reported in Table I below. A dash indicates that thetest was not conducted.

Plant species employed in these evaluations are reported by headerabbreviation and scientific name.

Compounds employed in this postemergence herbicidal evaluation and inthe preemergence evaluation in the following example are given acompound number and identified by name. Data in Table I are reported bycompound number.

PLANT SPECIES EMPLOYED IN HERBICIDAL EVALUATIONS

    ______________________________________                                        Header Abbreviation                                                                              Scientific Name                                            ______________________________________                                        TRZAS              Triticum aestivum                                          HORVW              Hordeum vulgare                                            GOSHI              Gossipium hirsutum                                         HELAN              Helianthus anuus                                           ZEAMX              Zea mays                                                   ALOMY              Alopercurus myosuroides                                    ECHCG              Echinocloa crus-galli                                      SETVI              Setaria viridis                                            GALAP              Galium aparine                                             STEME              Stellaria media                                            VERPE              Veronica persica                                           LAMPU              Lamium purpureum                                           VIOAR              Viola arvensis                                             SIDSP              Sida spinosa                                               AMBAR              Ambrosia artemesifolia                                     ABUTH              Abutilon Theophrasti                                       IPOPU              Ipomea purpurea                                            AMARE              Amaranthus retroflexus                                     ______________________________________                                    

COMPOUNDS EVALUATED AS HERBICIDAL AGENTS

    ______________________________________                                        Compound                                                                      Number                                                                        ______________________________________                                         1      2- (2-Chloro-4-pyridyl)oxy!-6- (p-fluorophenoxy)-                             methyl!pyridine                                                        2      2- (2-Chloro-4-pyridyl)oxy!-6- (3,5-difluorophenoxy)-                         methyl!pyridine                                                        3      2- (2-Chloro-4-pyridyl)oxy!-6- (p-tolyloxy)methyl!pyridine             4      2- (2-Chloro-4-pyridyl)oxy!-6-{ (2-chloro-4-pyridyl)oxy!-                     methyl}pyridine                                                        5      2- (2-Chloro-4-pyridyl)oxy!-6-{ (α,α,α-trifluoro            -m-                                                                           tolyl)oxy!methyl}pyridine                                              6      2- (α,α,α-Trifluoro-m-tolyl)oxy!-6-{ (α,.a            lpha.,α-trifluoro-m-                                                    tolyl)oxy!methyl}pyridine                                              7      2-{ (2-Chloro-4-pyridyl)oxy!methyl}-6- (α,α,α-tr            ifluoro-                                                                      m-tolyl)oxy!pyridine                                                   8      2-{ (6-Chloro-2-pyridyl)oxy!methyl}-6- (α,α,α-tr            ifluoro-                                                                      m-tolyl)oxy!pyridine                                                   9      2-{{ 1-Methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-                           methyl}-6- (α,α,α-trifluoro-m-tolyl)oxy!pyridine    10      2- (o-Fluorophenoxy)methyl!-6- (α,α,α-trifluoro-            m-tolyl)-                                                                     oxy!pyridine                                                          11      2- (α,α,α-Trifluoro-m-tolyl)oxy!-6- (o-tolyloxy)            methyl!-                                                                      pyridine                                                              12      2- (2,4-Difluorophenoxy)methyl!-6- (α,α,α-triflu            oro-m-                                                                        tolyl)oxy!pyridine                                                    13      2- (m-Fluorophenoxy)methyl!-6- (α,α,α-trifluoro-            m-tolyl)-                                                                     oxy!pyridine                                                          14      2- (p-Fluorophenoxy)methyl!-6- (α,α,α-trifluoro-            m-tolyl)-                                                                     oxy!pyridine                                                          15      2- (m-Tolyloxy)methyl!-6- (α,α,α-trifluoro-m-tol            yl)oxy!-                                                                      pyridine                                                              16      2- (p-Tolyloxy)methyl!-6- (α,α,α-trifluoro-m-tol            yl)oxy!-                                                                      pyridine                                                              17      2- (3,5-Difluorophenoxy)methyl!-6- (α,α,α-triflu            oro-m-                                                                        tolyl)oxy!pyridine                                                    18      2- (2,4-Difluorophenoxy)methyl!-6-{ 1-methyl-3-(trifluoro-                    methyl)pyrazol-5-yl!oxy}pyridine                                      19      2- (o-Fluorophenoxy)methyl!-6-{ 1-methyl-3-(trifluoro-                        methyl)pyrazol-5-yl!oxy}pyridine                                      20      2- (m-Fluorophenoxy)methyl!-6-{ 1-methyl-3-(trifluoro-                        methyl)pyrazol-5-yl!oxy}pyridine                                      21      2- (p-Fluorophenoxy)methyl!-6-{ 1-methyl-3-(trifluoro-                        methyl)pyrazol-5-yl!oxy}pyridine                                      22      2-{ 1-Methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-6-                           (o-tolyloxy)methyl!pyridine                                          23      2-{ 1-Methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-6-                           (m-tolyloxy)methyl!pyridine                                          24      2-{ 1-Methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-6-                           (p-tolyloxy)methyl!pyridine                                          25      2- (3,5-Difluorophenoxy)methyl!-6-{ 1-methyl-3-(trifluoro-                    methyl)pyrazol-5-yl!oxy}pyridine                                      26      2-{ 1-Methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-6-                           (α,α,α-trifluoro-m-tolyloxy)methyl!pyridine        27      2-{ (2-Chloro-4-pyridyl)oxy!methyl}-6-{ 1-methyl-3-(tri-                      fluoromethyl)pyrazol-5-yl!oxy}pyridine                                28      2-{ (6-Chloro-2-pyridyl)oxy!methyl}-6-{ 1-methyl-3-(tri-                      fluoromethyl)pyrazol-5-yl!oxy}pyridine                                29      2-{ 1-Methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-6-{{ 1-                     methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}methyl}-                           pyridine                                                              30      2-{ (5-Chloro-3-pyridyl)oxy!methyl}-6-{ 1-methyl-3-(tri-                      fluoromethyl)pyrazol-5-yl)oxy}pyridine                                31      2- (o-Chlorophenoxy)methyl!-6-{ 1-methyl-3-(trifluoro-                        methyl)pyrazol-5-yl!oxy}pyridine                                      32      2- (m-Chlorophenoxy)methyl!-6-{ 1-methyl-3-(trifluoro-                        methyl)pyrazol-5-yl!oxy}pyridine                                      33      2- (p-Chlorophenoxy)methyl!-6-{ 1-methyl-3-(trifluoro-                        methyl)pyrazol-5-yl!oxy}pyridine                                      34      2- (Benzyloxy)methyl!-6-{ 1-methyl-3-(trifluoromethyl)-                       pyrazol-5-yl!oxy}pyridine                                             ______________________________________                                    

    TABLE I                                                                          - Postemergence Herbicidal Evaluations of Test Compounds                       Compound Rate                                                                  Number (kg/ha) TRZAS HORVW GOSHI HELAN ZEAMX ALOMY ECHCG SETVI GALAP          STEME VERPE LAMPU VIOAR SIDSP AMBEL ABUTH IPOPU AMARE                           1 0.30 0 0 1 2 0 0 0 0 1 1 1 -- 2 1 1 1 1 3                                    2 0.30 0 0 1 2 1 0 0 0 2 1 1 -- 2 3 1 1 2 3                                    3 0.30 1 0 0 1 0 1 0 0 1 1 2 -- 2 1 1 0 1 2                                    4 0.30 0 1 3 3 3 0 -- 2 2 1 1 -- 5 -- -- -- 2 --                               5 0.30 0 0 4 4 3 0 -- 1 5 1 1 -- 7 -- -- -- 4 --                               6 0.48 3 2 3 4 2 2 3 2 4 4 4 3 7 5 3 4 4 5                                     7 0.48 3 0 5 4 2 4 3 3 5 4 5 4 5 5 3 4 4 5                                     8 0.48 3 2 3 3 1 3 1 1 4 4 3 3 4 4 3 3 4 4                                     9 0.30 0 0 3 3 0 0 -- 2 0 -- 3 1 3 -- -- 2 2 --                                10 0.30 0 0 2 2 0 0 -- 0 0 -- 0 0 1 -- -- 0 1 --                               11 0.30 0 0 2 3 0 0 -- 1 0 -- 1 0 1 -- -- 0 2 --                               12 0.30 0 0 2 4 0 0 -- 0 0 -- 2 0 2 -- -- 0 1 --                               13 0.30 0 0 4 3 0 1 -- 1 0 -- 1 1 6 -- -- 0 2 --                               14 0.30 1 0 2 2 0 1 -- 1 0 -- 1 0 6 -- -- 0 2 --                               15 0.30 0 0 4 2 0 0 -- 0 0 -- 2 0 4 -- -- 0 2 --                               16 0.30 0 0 2 1 0 0 -- 0 0 -- 2 0 1 -- -- 0 2 --                               17 0.30 0 0 5 2 0 1 -- 1 0 -- 0 1 6 -- -- 0 2 --                               18 0.30 0 0 2 3 0 2 -- 1 0 -- 6 1 6 -- -- 0 3 --                               19 0.30 0 0 2 2 0 1 -- 5 0 -- 1 0 6 -- -- 0 3 --                               20 0.30 2 4 -- 4 3 3 -- 3 4 4 8 -- -- -- 4 5 4 5                               21 0.48 3 4 2 5 0 4 0 3 5 4 5 0 6 0 0 0 4 5                                    22 0.30 2 2 -- 4 3 1 -- 2 3 4 7 -- -- -- 3 3 5 4                               23 0.30 1 2 -- 4 2 1 -- 2 2 1 7 -- -- -- 3 2 4 4                               24 0.30 1 1 2 2 0 1 -- 1 0 -- 6 4 5 -- -- 0 3 --                               25 0.30 0 0 4 3 0 1 -- 1 0 -- 7 3 7 -- -- 0 4 --                               26 0.30 0 1 4 4 0 2 1 1 4 3 6 -- 6 4 3 3 3 5                                   27 0.30 0 1 3 3 1 1 1 1 3 1 4 -- 4 3 1 1 2 2                                   28 0.30 0 0 3 3 1 1 0 1 3 0 3 -- 2 1 2 1 2 2                                   29 0.30 1 1 4 4 0 1 0 1 3 1 4 -- 3 4 3 2 3 3                                   30 0.30 0 0 3 3 3 0 -- 0 1 0 1 -- 1 -- -- -- 3 --                              31 0.30 0 0 3 3 3 0 -- 0 1 0 1 -- 1 -- -- -- 0 --                              32 0.30 0 0 2 3 3 0 -- 1 2 1 2 -- 5 -- -- -- 3 --                              33 0.30 0 0 2 3 3 0 -- 2 2 0 3 -- 7 -- -- -- 3 --                              34 0.24 2 1 3 2 2 1 -- 0 3 -- 3 1 6 -- -- 0 -- --                        

EXAMPLE 8 Preemergence herbicidal evaluation of test compounds

The preemergence herbicidal activity of the test compounds of thepresent invention is exemplified by the following tests in which theseeds of a variety of monocotyledonous and dicotyledonous plants areseparately mixed with potting soil and planted on top of soil inseparate containers. After planting, the cups are sprayed with theformulations described in Example 7 to provide the equivalent of about0.48 kg or 0.30 kg per hectare of test compound per container. Thetreated containers are then placed on greenhouse benches and cared forin accordance with conventional greenhouse procedures. Twenty days aftertreatment, the tests are terminated and each container is examined andrated according to the rating system provided in Example 7.

Data obtained are reported in Table II below. A dash indicates that thetest was not conducted. The compounds evaluated are reported by compoundnumber given in Example 7.

    TABLE II                                                                         - Preemergence Herbicidal Evaluations of Test Compounds                        Compound Rate                                                                  Number (kg/ha) TRZAS HORVW GOSHI HELAN ZEAMX ALOMY ECHCG SETVI GALAP          STEME VERPE LAMPU VIOAR SIDSP AMBEL ABUTH IPOPU AMARE                           1 0.30 0 0 0 0 0 0 0 1 0 0 5 0 2 0 0 0 0 4                                     2 0.30 0 0 0 0 0 0 0 0 0 0 2 0 1 0 0 0 0 1                                     3 0.30 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0                                     4 0.30 0 0 0 0 0 0 -- 6 0 0 9 -- 3 -- -- -- 1 --                               5 0.30 0 0 0 0 0 0 -- 0 0 0 1 -- 5 -- -- -- 0 --                               6 0.48 0 0 2 1 0 0 1 2 0 0 0 0 0 1 0 0 0 7                                     7 0.48 0 0 0 0 0 0 2 4 0 0 1 2 0 1 1 0 1 7                                     8 0.48 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1                                     9 0.30 0 0 0 0 0 0 -- 0 0 -- 1 0 1 -- -- 0 0 --                                10 0.30 0 0 0 0 0 0 -- 0 0 -- 0 0 0 -- -- 0 0 --                               11 0.30 0 0 0 0 0 0 -- 0 0 -- 0 0 0 -- -- 0 0 --                               12 0.30 0 0 0 0 0 0 -- 0 0 -- 0 0 0 -- -- 0 0 --                               13 0.30 0 0 0 0 0 0 -- 0 0 -- 1 0 2 -- -- 0 0 --                               14 0.30 0 0 0 0 0 0 -- 0 0 -- 1 0 1 -- -- 0 0 --                               15 0.30 0 0 0 0 0 0 -- 0 0 -- 1 0 0 -- -- 0 0 --                               16 0.30 0 0 0 0 0 0 -- 0 0 -- 0 0 0 -- 0 0 0 --                                17 0.30 0 0 0 0 0 0 -- 0 0 -- 1 0 6 -- -- 0 0 --                               18 0.30 0 0 0 0 0 1 -- 0 0 -- 7 0 7 -- -- 0 0 --                               19 0.30 0 0 0 0 0 0 -- 0 0 -- 5 0 5 -- -- 0 0 --                               20 0.30 1 2 -- 0 1 2 -- 0 3 6 9 -- -- -- 1 3 2 8                               21 0.48 0 0 1 0 0 4 0 3 2 4 9 0 8 0 1 0 1 9                                    22 0.30 1 0 -- 0 0 0 -- 0 1 4 8 -- -- -- 1 0 0 8                               23 0.30 0 0 -- 0 0 0 -- 0 3 0 7 -- -- -- 0 0 0 7                               24 0.30 0 0 0 0 0 0 -- 0 0 -- 6 0 1 -- -- 0 0 --                               25 0.30 0 0 0 0 0 0 -- 0 0 -- 7 4 7 -- -- 0 0 --                               26 0.30 2 2 0 0 0 1 0 7 0 3 8 4 5 0 0 0 0 6                                    27 0.30 0 0 0 2 0 1 3 2 0 4 9 4 8 0 0 0 1 0                                    28 0.30 0 0 0 0 0 0 0 2 0 0 7 0 4 0 0 0 0 6                                    29 0.30 0 0 0 0 0 2 4 1 0 0 9 5 7 0 0 0 2 0                                    30 0.30 0 0 0 0 0 0 -- 1 0 0 0 -- 0 -- -- -- 0 --                              31 0.30 0 0 0 0 0 0 -- 1 0 0 0 -- 0 -- -- -- 0 --                              32 0.30 0 0 0 0 0 0 -- 1 0 0 5 -- 3 -- -- -- 0 --                              33 0.30 0 0 0 0 0 0 -- 1 0 0 3 -- 3 -- -- -- 0 --                              34 0.48 1 4 0 0 3 4 -- 7 0 -- 5 0 2 -- -- 0 -- --                        

What is claimed is:
 1. A compound having the structural formula##STR93## wherein one of the groups A and B representsphenyl optionallysubstituted with one or more halogen atoms, nitro groups, cyano groups,amino groups, hydroxyl groups, C₁ -C₄ alkyl groups, C₁ -C₄ haloalkylgroups, C₁ -C₄ alkoxy groups, C₁ -C₄ haloalkoxy groups or C₁ -C₄haloalkylsulfonyl groups, or 1- or 2-naphthyl optionally substitutedwith one or more halogen atoms, nitro groups, cyano groups, aminogroups, hydroxyl groups, C₁ -C₄ alkyl groups, C₁ -C₄ haloalkyl groups,C₁ -C₄ alkoxy groups, C₁ -C₄ haloalkoxy groups or C₁ -C₄halo-alkylsulfonyl groups;the other one of groups A and B represents apyrazolyl group optionally substituted with one or more halogen atoms,nitro groups, cyano groups, amino groups, hydroxyl groups, C₁ -C₄ alkylgroups, C₁ -C₄ haloalkyl groups, C₁ -C₄ alkoxy groups, C₁ -C₄ haloalkoxygroups or C₁ -C₄ haloalkylsulfonyl groups; X and Y are eachindependently O or S; R is C₁ -C₆ alkyl, C₁ -C₆ haloalkyl, C₁ -C₆alkoxy, C₁ -C₆ haloalkoxy, C₁ -C₆ alkylthio or di(C₁ -C₆ alkyl)amino; mis an integer of 0, 1 or 2; and n is an integer of 0 or
 1. 2. Thecompound according to claim 1 whereinB represents phenyl optionallysubstituted with one or more halogen atoms, C₁ -C₄ alkyl groups, C₁ -C₄haloalkyl groups, C₁ -C₄ alkoxy groups, C₁ -C₄ haloalkoxy groups or C₁-C₄ haloalkylsulfonyl groups;A represents a pyrazolyl group optionallysubstituted with one or more halogen atoms, C₁ -C₄ alkyl groups, C₁ -C₄haloalkyl groups, C₁ -C₄ alkoxy groups, C₁ -C₄ haloalkoxy groups or C₁-C₄ haloalkylsulfonyl groups;R is C₁ -C₄ alkyl, C₁ -C₄ haloalkyl, C₁ -C₄alkoxy, C₁ -C₄ haloalkoxy, C₁ -C₄ alkylthio or di(C₁ -C₄ alkyl)amino;and m and n are each independently an integer of 0 or
 1. 3. The compoundaccording to claim 2 whereinB represents phenyl optionally substitutedwith one to three halogen atoms, C₁ -C₄ alkyl groups or C₁ -C₄ haloalkylgroups;A represents a pyrazolyl group optionally substituted with one tothree halogen atoms, C₁ -C₄ alkyl groups or C₁ -C₄ haloalkyl groups;Xand Y are O; and R is C₁ -C₄ alkyl, C₁ -C₄ haloalkyl, C₁ -C₄ alkoxy orC₁ -C₄ haloalkoxy.
 4. The compound according to claim 3 whereinA is5-pyrazolyl optionally substituted with one or two methyl groups ortrifluoromethyl groups;B is phenyl optionally substituted with one ortwo fluorine atoms, chlorine atoms, methyl groups or trifluoromethylgroups; and m and n are
 0. 5. A method for controlling undesirable plantspecies which comprises applying to the foliage of said plants or to thesoil or water containing seeds or other propagating organs thereof, aherbicidally effective amount of a compound having the structuralformula according to claim
 1. 6. The method according to claim 5whereinone of groups A and B represents phenyl optionally substitutedwith one or more halogen atoms, C₁ -C₄ alkyl groups, C₁ -C₄ haloalkylgroups, C₁ -C₄ alkoxy groups, C₁ -C₄ haloalkoxy groups or C₁ -C₄haloalkylsulfonyl groups;and the other of groups A and B represents apyrazolyl group optionally substituted with one or more halogen atoms,C₁ -C₄ alkyl groups, C₁ -C₄ haloalkyl groups, C₁ -C₄ alkoxy groups, C₁-C₄ haloalkoxy groups or C₁ -C₄ haloalkylsulfonyl groups;R is C₁ -C₄alkyl, C₁ -C₄ haloalkyl, C₁ -C₄ alkoxy, C₁ -C₄ haloalkoxy, C₁ -C₄alkylthio or di(C₁ -C₄ alkyl)amino; and m and n are each independentlyan integer of 0 or
 1. 7. The method according to claim 6 whereinBrepresents phenyl optionally substituted with one to three halogenatoms, C₁ -C₄ alkyl groups or C₁ -C₄ haloalkyl groups;A represents apyrazolyl group optionally substituted with one to three halogen atoms,C₁ -C₄ alkyl groups or C₁ -C₄ haloalkyl groups;X and Y are O; and R isC₁ -C₄ alkyl, C₁ -C₄ haloalkyl, C₁ -C₄ alkoxy or C₁ -C₄ haloalkoxy. 8.The method according to claim 7 whereinA is 5-pyrazolyl optionallysubstituted with one or two methyl groups or trifluoromethyl groups;B isphenyl optionally substituted with one or two fluorine atoms, chlorineatoms, methyl groups or trifluoromethyl groups; and m and n are
 0. 9.The method according to claim 5 which comprises applying said compoundto the foliage of said plants or to the soil or water containing seedsor other propagating organs thereof at a rate of about 0.016 kg/ha to4.0 kg/ha.
 10. A herbicidal composition which comprises an inert solidor liquid carrier and a herbicidally effective amount of a compoundhaving the structural formula according to claim
 1. 11. The compositionaccording to claim 10 wherein one of groups A and B represents phenyloptionally substituted with one or more halogen atoms, C₁ -C₄ alkylgroups, C₁ -C₄ haloalkyl groups, C₁ -C₄ alkoxy groups, C₁ -C₄ haloalkoxygroups or C₁ -C₄ haloalkylsulfonyl groups;the other of groups A and Brepresents a pyrazolyl group optionally substituted with one or morehalogen atoms, C₁ -C₄ alkyl groups, C₁ -C₄ haloalkyl groups, C₁ -C₄alkoxy groups, C₁ -C₄ haloalkoxy groups or C₁ -C₄ haloalkylsulfonylgroups;R is C₁ -C₄ alkyl, C₁ -C₄ haloalkyl, C₁ -C₄ alkoxy, C₁ -C₄haloalkoxy, C₁ -C₄ alkylthio or di(C₁ -C₄ alkyl)amino; and m and n areeach independently an integer of 0 or
 1. 12. The composition accordingto claim 11 whereinB is phenyl optionally substituted with one to threehalogen atoms, C₁ -C₄ alkyl groups or C₁ -C₄ haloalkyl groups;A is apyrazolyl group optionally substituted with one to three halogen atoms,C₁ -C₄ alkyl groups or C₁ -C₄ haloalkyl groups; X and Y are O; and R isC₁ -C₄ alkyl, C₁ -C₄ haloalkyl, C₁ -C₄ alkoxy or C₁ -C₄ haloalkoxy. 13.The composition according to claim 10 wherein A is5-pyrazolyl optionallysubstituted with one or two methyl groups or trifluoromethyl groups;B isphenyl optionally substituted with one or two fluorine atoms, chlorineatoms, methyl groups or trifluoromethyl groups; and m and n are
 0. 14.The compound according to claim 4 selected from the group consistingof2- (m-fluorophenoxy)methyl!-6-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-pyridine; 2-(p-fluorophenoxy)methyl!-6-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-pyridine: 2-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-6-(o-tolyloxy)methyl!pyridine; 2-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-6-(m-tolyloxy)methyl!pyridine; 2-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-6-(p-tolyloxy)methyl!pyridine; 2- (3,5-difluorophenoxy)methyl!-6-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}pyridine; 2-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-6-(α,α,.alpha.-trifluoro-m-tolyloxy)methyl!pyridine; 2-(o-chlorophenoxy)methyl!-6-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-pyridine; 2-(m-chlorophenoxy)methyl!-6-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-pyridine; 2-(p-chlorophenoxy)methyl!-6-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-pyridine; and 2-(benzyloxy)methyl!-6-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}pyridine.
 15. The methodaccording to claim 6 wherein the compound is selected from the groupconsisting of2- (m-fluorophenoxy)methyl!-6-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-pyridine; 2-(p-fluorophenoxy)methyl!-6-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-pyridine; 2-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}6-(o-tolyloxy)methyl!pyridine; 2-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}6-(m-tolyloxy)methyl!pyridine; 2-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}6-(p-tolyloxy)methyl!pyridine; 2- (3,5-difluorophenoxy)methyl!-6-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}pyridine; 2-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-6-(α,α,.alpha.-trifluoro-m-tolyloxy)methyl!pyridine; 2-(o-chlorophenoxy)methyl!-6-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-pyridine; 2-(m-chlorophenoxy)methyl!-6-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-pyridine; 2-(p-chlorophenoxy)methyl!-6-{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}-pyridine; and 2-(benzyloxy)methyl!-6{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}pyridine.
 16. The compoundaccording to claim 1 whereinA represents a phenyl group optionallysubstituted with one or two fluorine atoms, chlorine atoms, methylgroups or trifluoromethyl groups; B represents a 5-pyrazolyl groupoptionally substituted with one or two methyl groups or trifluoromethylgroups; and m and n are
 0. 17. The compound according to claim 16 whichis 2-{{1-methyl-3-(trifluoromethyl)pyrazol-5-yl!oxy}methyl}-6-(α,.alpha.,α-trifluoro-m-tolyloxy)pyridine.